Study of Z boson production in PbPb collisions at nucleon-nucleon centre of mass energy = 2.76 TeV

A search for Z bosons in the μ+μ− decay channel has been performed in PbPb collisions at √ sNN = 2.76 TeV with the CMS detector at the LHC, in a 7.2 μb−1 data sample. The number of opposite-sign muon pairs observed in the 60–120 GeV/c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of (33.8± 5.5(stat) ± 4.4(syst)) × 10−8, in the |y| < 2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions. Submitted to Physical Review Letters ∗See Appendix A for the list of collaboration members ar X iv :1 10 2. 54 35 v1 [ nu cl -e x] 2 6 Fe b 20 11